linux-kernel - Re: [PATCH] x86/virt/tdx: Use precalculated TDVPR page physical address

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Message-ID: <872c17f3-9ded-46b2-a036-65fc2abaf2e6@intel.com>
Date: Mon, 20 Oct 2025 07:14:31 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Sean Christopherson <seanjc@...gle.com>,
 Dave Hansen <dave.hansen@...ux.intel.com>
Cc: linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
 Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
 x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
 "Kirill A. Shutemov" <kas@...nel.org>,
 Rick Edgecombe <rick.p.edgecombe@...el.com>,
 Paolo Bonzini <pbonzini@...hat.com>, Kai Huang <kai.huang@...el.com>,
 Isaku Yamahata <isaku.yamahata@...el.com>,
 Vishal Annapurve <vannapurve@...gle.com>, Thomas Huth <thuth@...hat.com>,
 Adrian Hunter <adrian.hunter@...el.com>, linux-coco@...ts.linux.dev,
 kvm@...r.kernel.org, Farrah Chen <farrah.chen@...el.com>
Subject: Re: [PATCH] x86/virt/tdx: Use precalculated TDVPR page physical
 address

On 10/20/25 06:57, Sean Christopherson wrote:
> Why do these structures track struct page everywhere?

I asked for it at some point. It allows an unambiguous reference to
normal, (mostly) allocated physical memory. It means that you (mostly)
can't accidentally swap in a virtual address, pfn, or something else
that's not a physical address into the variable.

The TDX ABI is just littered with u64's. There's almost no type safety
anywhere. This is one place to bring a wee little bit of order to the chaos.

In a perfect world, we'd have sparse annotations for the vaddr, paddr,
pfn, dma_addr_t and all the other address spaces. Until then, I like
passing struct page around.